• Title, Summary, Keyword: Surface Coil

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An Optimization of Inductive Coil Design for Thixoforging and Its Experimental Study (반용융 단조를 위한 유도가열용 코일설계의 최적화 및 실험적 연구)

  • Jung, Hong-Kyu;Kim, Nam-Seok;Kang, Chung-Gil
    • Journal of Korea Foundry Society
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    • v.19 no.5
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    • pp.393-402
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    • 1999
  • The reheating of the billet in the semi-solid state as quickly and homogeneously as possible is one of the most important aspects. From this point of view, an optimal design of the induction coil is necessary. The objective of inductive coil designsi a uniform induction heating over the length of the billet. The effect of coil length, diameter, the gap between coil surface and billet and axial position of the billet on temperature distribution of billet has been investigated. These design parameters have an important effectiveness on the electro-magnetic field. Therefore, in this study an optimal coil design to minimize electromagnetic ed effect will be proposed by defining the relationship between billet length and coil length. In particular, key point in induction heating process is focussed on optimizing the coil design with regard to the size of the heating billet and the frequency of induction heating system. After demonstrating the suitability of an optimal coil design through the FEM simulation of the induction heating process, the results of the coil design are also applied to the reheating process to obtain a fine globular microstructure. Its considered that the reheating conditions of aluminum alloys for thixoforging and a new CAE model of the induction heating process are very useful for thixoforging practitioners including induction heating ones.

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Inductive Micro Thin Film Sensor for Metallic Surface Crack Detection (금속 표면결함 검출용 자기유도 마이크로 박막 센서)

  • Kim, Ki-Hyeon
    • Journal of the Korean Society for Nondestructive Testing
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    • v.28 no.5
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    • pp.395-400
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    • 2008
  • Alternating magnetic field was used for detection of surface flaws on nonmagnetic and magnetic metallic specimens. The nondestructive sensor probe was composed of the planar coil with inductive magnetic thin film yoke as a sensing component and a single straight typed exciting coil. The planar inductive coil sensor with magnetic yoke was fabricated by sputtering, electroplating, dry etching and photolithography process. The alternative currents with the range of 0.1A to 1.0A (0.7 MHz to 1.8 MHz) were applied to the exciting coil. The specimens were prepared with the slit shaped artificial surface flaws (minimum depth and width; 0.5 mm) on metallic plate (Al; nonmagnetic metal and FeC; magnetic metal). The detected signal for the positions and shapes of surface flaws on specimens were obtained with high sensitivity and high signal to ratio. The measured output signals by the non-contacted scanning on surface of FeC specimen with micron-sized crack were converted to the images of the flaws. And these results were compared with the optical images, respectively.

A Study on the Insertional Coil of MRI Device for Diagnosis (진단용 자기공명영상장치의 삽입 코일에 관한 연구)

  • Lee, Yong-Moon;Lim, Keun-Ho;Seo, Dae-Keon;Kim, Wang-Gon;Hong, Jin-Woong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.33-37
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    • 2003
  • Endovaginal and endorectal receiver only surface coil were designed for MR imaging(MRI) and $^1H$ MR spectroscopy(MRS) for the uterine cervix and the prostate. The shape of endovaginal coil wire was rectangular with round comer. The shape of endorectal coil wire was long elliptic shape during insertion and circular shape after insertion. Conventional spin echo and fast spin echo sequences were used as T1 and T2 weighted imaging sequences, respectively. 3D volume localized in vivo $^1H$ MR spectroscopy of the human cervix and prostate was performed using PRESS or STEAM localization method. Using home-built endvaginal and endorectal coils, excellent T1 and T2 images were obtained to visualize early cervical and prostate tumors. 3D volume localized in vivo $^1H$ MRS was useful to differentiate the cancerous tissue from the normal tissue.

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Study of the capability of metallic coils immersed with protein solution as embolic masterials (색전용 금속 코일 개발과 단백질 처리 후 혈전성에 대한 연구)

  • Lee, Y.S.;Kim, T.S.;Kim, H.C.;Shin, K.M.;Park, J.H.
    • Proceedings of the KOSOMBE Conference
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    • v.1997 no.11
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    • pp.347-349
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    • 1997
  • In this study, we designed a vascular occlusion device based on the principle that slowing blood flow would induce thrombosis. Tungsten, stainless steel and platinum were tested for finding a good embolic metallic coil. The primary coil and the second coil were done with heat treatment or different time. The pitch distance and the shape retention capability of second coil were characterized by SEM. To increase thrombogenicity, we tried to treat different proteins on steel coils: thrombin, gelatin and both gelatin and thrombin. To verify protein materials treated on coils, the surface of coil treated with different proteins were characterized using Laser Raman Spectrophotometer. After observation of embolic coils, the peptides bonds on theirs' surface were found. In order to compare the thrombogenicity of different embolic agents, we measured whole blood clotting time.

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Thermal Performance of a Spirally Coiled Finned Tube Heat Exchanger Under Wet-Surface Conditions

  • Wongwises Somchai;Naphon Paisarn
    • Journal of Mechanical Science and Technology
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    • v.20 no.2
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    • pp.212-226
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    • 2006
  • This paper is a continuation of the authors' previous work on spiral coil heat exchangers. In the present study, the heat transfer characteristics and the performance of a spirally coiled finned tube heat exchanger under wet-surface conditions are theoretically and experimentally investigated. The test section is a spiral-coil heat exchanger which consists of a steel shell and a spirally coiled tube unit. The spiral-coil unit consists of six layers of concentric spirally coiled finned tubes. Each tube is fabricated by bending a 9.6 mm diameter straight copper tube into a spiral-coil of four turns. The innermost and outermost diameters of each spiral-coil are 145.0 and 350.4 mm, respectively. Aluminium crimped spiral fins with thickness of 0.6 mm and outer diameter of 28.4 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Air and water are used as working fluids in shell side and tube side, respectively. The experiments are done under dehumidifying conditions. A mathematical model based on the conservation of mass and energy is developed to simulate the flow and heat transfer characteristics of working fluids flowing through the heat exchanger. The results obtained from the present model show reasonable agreement with the experimental data.

Design of an Electromagnetically-driven Micromirror Through the Coupled Physics Analyses (복합장 해석에 의한 전자력 구동방식의 마이크로미러 설계)

  • Han, Seung-Oh;Kim, Byoung-Min;Pak, Jung-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.2
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    • pp.380-384
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    • 2010
  • A micromirror for a laser display system actuated by the electromagnetic force induced by the surface coil and the permanent magnet was designed and analyzed through the coupled physics analyses incorporating the electromagnetics, mechanics, and electrothermal analysis because the mechanical rotation of the micromirror is driven by the electromagnetic driving force. The proposed micromirror has two torsion beams to sustain the mirror plate which has surface coils on the top and the two permanent magnets exists on both sides of the micromirror for an external magnetic field source. The designed micromirror has the resonant frequency of 3.82kHz. When the magnetic field of the permanent magnet is 0.4T, the coil has 4 turns, and the current density of coil is 3.6A/$mm^2$, the estimated z axis displacement of the mirror plate edge is 0.23mm which corresponds to the rotation angle of $14.2^{\circ}$. When considering the joule heating in the current-carrying coil, the maximum temperature of the mirror plate is obtained as 300.045K, which induces the negligible changes in the rotation angle and the resistance of the coil.

The Study on Reliability Improvement in Eddy Current Inspection by Signal Characteristic Optimization of Multi-coil Array Probe (다중센서 신호특성 최적화를 통한 와전류검사 신뢰성 개선연구)

  • Ahn, Y.S.;Gil, D.S.;Park, S.G.
    • Journal of the Korea Society For Power System Engineering
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    • v.14 no.2
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    • pp.60-64
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    • 2010
  • This paper introduces reliability improvement and time saving in eddy current inspection by signal characteristic optimization of multi-coil eddy current array probe. In the past, Multi-coil array probe and single probe were used for the gas turbine rotor surface inspection & defect evaluation. The multi-coil array probe was used for the broad area inspection. But the signal deviations among multi-coil array probe are maximum 28% in commercial probe. This differences were considered to impedance differences among coils, so it is very difficult to evaluate exact defect size. The signal deviations among multi-coil array probe are maximum 28% in commercial probe. So, single coil inspection was used for exact defect sizing. The purpose of this study is to improve signal deviations of multi-coil array probe. The introduced new technology can improves this deviation by adjusting input voltage in each coil. At first, apply same voltage in each coil and collect signal amplitude of each coil. And calculate new input voltage based on signal amplitude of each coil. If the signal amplitude deviation is within 5% among multi-coil array probe, the signal amplitude of multi-coil array probe is reliable. The proposed technology gives 2% signal deviation among multi-coil array probe. The proposed new technology gives reliability improvement and inspection time saving in eddy current inspection.

FPCB-based Birdcage-Type Receiving Coil Sensor for Small Animal 1H 1.5 T Magnetic Resonance Imaging System (소 동물 1H 1.5 T 자기공명영상 장치용 유연인쇄기판 기반 새장형 수신 코일 센서)

  • Ahmad, Sheikh Faisal;Kim, Hyun Deok
    • Journal of Sensor Science and Technology
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    • v.26 no.4
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    • pp.245-250
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    • 2017
  • A novel method to implement a birdcage-type receiving coil sensor for use in a magnetic resonance imaging(MRI) system has been demonstrated employing a flexible printed circuit board (FPCB) fabrication technique. Unlike the conventional methods, the two-dimensional shape of the coil sensor is first implemented as a FPCB and then it is attached to the surface of a cylindrical supporting structure to implement the three-dimensional birdcage-type coil sensor. The proposed method is very effective to implement object-specific MRI coil sensors especially for small animal measurements in research and preclinical applications since the existing well-developed FPCB-based techniques can easily meet the requirements on accuracies and costs during coil implement process. The performances of the coil sensor verified through $^1H$ 1.5T MRI measurements for small animals and it showed excellent characteristics by providing a high spatial precision and a high signal-to-noise ratio.

Development of a 1.8T HTS Insert Coil for High Field Magnet (고자장 자석용 1.8T HTS insert 코일 개발)

  • Bae, Joon-Han;Seong, Ki-Chul
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.6
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    • pp.1035-1038
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    • 2007
  • We designed and manufactured a 1.8T high temperature superconducting(HTS) insert coil for a NMR magnet operated at 4.2 K. Suitable HTS superconductor and HTS coil were carefully designed and developed. We have selected multi-filamentary Bi2223 conductor fabricated by American Superconductor Corporation(AMSC). The selected conductor consists of Bi2223 filaments of 55, silver stabilizer and stainless steel reinforcement tapes. Therefore, it shows good hoop strength as well as compression tolerance. The conductor has a tape cross-section of 0.31mm x 4.8mm. the Bi2223 conductor shows large anisotropy of critical current. The critical current of conductor in magnetic field parallel to the flat surface are much higher than that in magnetic field perpendicular. The HTS coil has an inner diameter of 78 mm, an outer diameter of 127 mm and a coil length of 600 mm. In this paper, the detailed design, fabrication and test results on the HTS insert coil are presented.

Study on Coil Insulation of HTS Transformer with Simulated Electrode (고온초전도 코일의 모의 전극계에서의 절연연구)

  • 정종만;백승명;이정원;곽동순;김상현
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.420-423
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    • 2002
  • In this paper the characteristics of surface flashover for high temperature superconducting transformer(HTS) was discussed. The transformer, will be developed in the shell type with double pancake coil, isn't developed yet in the world. We conducted experiment of surface flashover that could occur in the windings of the transformer. First, we distinguished the surface flashover with electrode alignment into two type, such as parallel and vertical, and then compared with each characteristics of surface flashover. And the surface flashover with metallic particle was tested, it was also affected by the particle position. .

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